This proposal is the support of a broad area of research in the biosynthesis and structure of complex polysaccharides and glycoproteins. We plan to undertake studies in the following areas: 1. The mechanism of biosynthesis of complex polysaccharides and glycoproteins present in human lymphocytes; 2. The role of the carbohydrate moiety of human histocompatibility antigens will be studied by degrading the HL-A antigen with pronase to obtain a glycopeptide and by degrading the glycan moiety with glycosidases; 3. A study of the structure and biosynthesis of an unusual glycoprotein present in the cell envelope of Halobacteria will be undertaken. The biosynthesis appears to involve isoprenyl phosphate derivatives and may be a model for glycoprotein synthesis in animal tissues. Bibliographic references: Wedgwood, J.F., Strominger, J.L. and Warren, C.D. Transfer of Sugars from nucleoside diphosphosugar compounds to endogenous and synthetic dolichyl phosphate in human lymphocytes. J. Biol. Chem 249:6316-6324. (1974). Rubenstein, P.A. and Strominger, J.L. Enzymatic synthesis of cytidine diphosphate 3,6-dideoxyhexoses: VII. Mechanistic roles of enzyme E1 and pyridoxamine-5'-phosphate in the formation of CDP-4-keto-3, 6-dideoxy-D-glucose from CDP-4-keto-6-deoxy-D-glucose. J. Biol. Chem. 249: 3782-3788 (1974).